Electrophoresis coating liquid, electronic ink layer and electrophoresis display assembly

Abstract

The invention discloses electrophoretic coating liquid, an electronic ink layer and an electrophoretic display assembly, and relates to the technical field of electronic paper display. The electrophoresis coating liquid provided by the invention contains the surfactant, the rheological agent, the water-based resin adhesive, the defoaming agent, the emulsifier and the microcapsules, and by controlling the particle size distribution of the microcapsules, the microcapsules with the particle size D10 of 20-25 microns, the particle size D90 of 45-50 microns and the particle size D50 of 27-30 microns are selected, so that local deformation of large-particle-size capsules caused by stress concentration in the coating and drying process is avoided; in addition, the small-particle-size capsule shortens the migration path of electrophoretic particles, so that the electric field driving efficiency is improved, and the response time is effectively prolonged. By optimizing the ratio of the microcapsules to the water-based resin adhesive, the water-based resin adhesive can fill gaps of the microcapsules more sufficiently, a uniform supporting network is formed around the microcapsules after curing, capsule breakage caused by mechanical extrusion is reduced, and the breakage rate of the capsules is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of electronic paper display, and particularly relates to an electrophoretic coating solution, an electronic ink layer and an electrophoretic display component. Background Art

[0002] Under the background of green and low-carbon development, electronic paper is applied to more and more industries due to its bistable characteristics. Based on the principle of electrophoretic display, electronic paper realizes color display through the orderly migration of electrophoretic particles in the microcapsule structure. Its core advantage is that an electric field needs to be applied only during refreshing, and the image is maintained with zero power consumption during static display. Compared with traditional LCD (Liquid Crystal Display) / LED (

[0003] Light Emitting Diode) display screens, the energy consumption of electronic paper display screens is extremely low. However, at present, mainstream electronic paper products are prone to obvious afterimage phenomena during dynamic display, resulting in poor visual experience, which is caused by too long response time. How to improve the response time of electronic paper is of great significance for expanding its applications in emerging fields such as interactive electronic signs and wearable devices. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an electrophoretic coating solution, an electronic ink layer and an electrophoretic display component, so as to solve the problem of long response time of electronic paper in the prior art.

[0005] To solve the above problems, the present invention proposes the following technical solutions:

[0006] In a first aspect, the present invention provides an electrophoretic coating solution, which comprises the following components in parts by weight:

[0007] Surfactant: 0.1 - 3.0 parts;

[0008] Rheology modifier: 1.0 - 6.0 parts;

[0009] Water-based resin binder: 10 - 35 parts;

[0010] Defoamer: 0.1 - 2.0 parts;

[0011] Emulsifier: 0.1 - 3.0 parts;

[0012] Microcapsules, the microcapsules include a capsule wall and an electrophoretic solution, the capsule wall is used to coat the electrophoretic solution, and the electrophoretic solution contains electrophoretic particles;

[0013] The particle size D10 of the microcapsules is 20 - 25 μm, D90 is 45 - 50 μm, D50 is 27 - 30 μm; the weight ratio of the microcapsules to the water-based resin binder is 3:1 - 8:1.

[0014] A further technical solution is that the viscosity of the electrophoretic coating solution is 20 to 200 cp.

[0015] A further technical solution is that the weight ratio of the microcapsules to the aqueous resin binder is 3:1 to 5:1.

[0016] A further technical solution is that the aqueous resin binder includes at least one of aqueous polyurethane, aqueous acrylic acid, aqueous epoxy resin, aqueous styrene-butadiene resin, and aqueous polyester.

[0017] A further technical solution is that the surfactant includes at least one of acrylic surfactants and polyether surfactants.

[0018] A further technical solution is that the rheology modifier includes at least one of hydroxypropyl methylcellulose and polyurethane.

[0019] A further technical solution is that the defoamer includes at least one of silicone defoamers and polymer defoamers.

[0020] A further technical solution is that the emulsifier includes at least one of sorbitan fatty acid esters, polysorbates, polyvinyl alcohol, span, and polysorbates.

[0021] A further technical solution is that the wall thickness of the microcapsules is 0.5 to 2 μm; the electrophoretic solution includes the following components in parts by weight:

[0022] Electrophoretic particles 17% to 65%; solvent 30% to 80%; the sum of the charge control agent and the stabilizer is 3% to 5%.

[0023] The electrophoretic particles have the function of reflecting or scattering or absorbing light to achieve the final display effect of the electronic paper. The particle size of the electrophoretic particles is between 10 nm and 2 μm, and mainly includes, but is not limited to, one of titanium dioxide, carbon black, copper chromite black, iron manganese black, and composite particles. The composite particles are polymer-modified, and the polymer modification is carried out in two steps. In the first step, the inorganic particles are surface-modified with a surface modifier, and in the second step, the organic monomer is attached to the silane coupling agent through a free radical reaction; the surface modifier includes, but is not limited to, titanate coupling agents, aluminate coupling agents, silane coupling agents, surfactants, or initiators, and the organic monomers include, but are not limited to, at least one of methyl methacrylate, aniline, o-methylaniline, lauryl methacrylate, stearyl methacrylate, vinyl silicone oil, and styrene; the initiator is at least one of benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, azobisisoheptonitrile, potassium persulfate, ammonium persulfate, and dimethyl azobisisobutyrate.

[0024] The solvent is one of pure water, ethanol, butanol, benzene, toluene, xylene, trimethylbenzene, carbon tetrachloride, dichloromethane, tetrachloroethylene, alkane solvent or isoparaffin solvent, silicone oil, vegetable oil, and castor oil. The charge control agent is at least one of cationic surfactant, anionic surfactant, nonionic surfactant or zwitterionic surfactant. The stabilizer is polyvinylpyrrolidone.

[0025] In a second aspect, the present invention provides a method for preparing an electrophoretic coating solution, which includes the following steps: providing each component according to the electrophoretic coating solution described in the first aspect and performing a mixing process to obtain the electrophoretic coating solution.

[0026] In a third aspect, the present invention provides an electronic ink layer, which is obtained by coating and drying the electrophoretic coating solution described in the first aspect.

[0027] A further technical solution thereof is that the thickness of the dried electronic ink layer is 10 - 25 μm.

[0028] A further technical solution thereof is that the thickness of the dried electronic ink layer is 10 - 15 μm.

[0029] In a fourth aspect, the present invention provides an electrophoretic display component, which sequentially includes an upper substrate, an electronic ink layer, an adhesive layer and a lower substrate from top to bottom; wherein, the electronic ink layer is the electronic ink layer described in the third aspect, or is obtained by coating and drying the electrophoretic coating solution described in the first aspect.

[0030] Compared with the prior art, the technical effects that the present invention can achieve include:

[0031] The electrophoretic coating solution provided by the present invention contains surfactants, rheological agents, aqueous resin binders, defoamers, emulsifiers and microcapsules. By controlling the particle size distribution of the microcapsules, microcapsules with a D10 particle size of 20 - 25 μm, a D90 particle size of 45 - 50 μm, and a D50 particle size of 27 - 30 μm are selected to avoid local deformation (such as flattening or prismatic shape) caused by stress concentration of large particle size capsules during the coating and drying process; in addition, small particle size capsules shorten the migration path of electrophoretic particles (the migration time is proportional to the square of the path), improve the electric field driving efficiency, and effectively improve the response time. At the same time, the surface area of small particle size microcapsules increases, and the electric field distribution within the unit volume is more uniform, further accelerating the charge migration.

[0032] Furthermore, by optimizing the ratio of the microcapsules to the aqueous resin binder in the present invention, the aqueous resin binder can more fully fill the gaps between the microcapsules, and form a uniform support network around the microcapsules after curing, reducing the capsule rupture caused by mechanical extrusion and effectively reducing the capsule breakage rate. Description of the Drawings

[0033] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings required for the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, other accompanying drawings can be obtained based on these drawings without creative efforts.

[0034] Figure 1 It is a photograph of the electro-ink layer obtained in Example 6.

[0035] Figure 2 It is a photograph of the electro-ink layer obtained in Comparative Example 6.

[0036] Figure 3 It is a schematic structural diagram of an electrophoretic display component; the reference numerals in the figure are: microcapsule 1, upper substrate 2, electro-ink layer 3, adhesive layer 4, and lower substrate 5.

[0037] Figure 4 It is a photograph of the electro-ink layer of Comparative Example 2. Specific Embodiments

[0038] The technical solutions in the embodiments will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Similar component reference numerals in the drawings represent similar components. Obviously, the embodiments described below are only some embodiments of the present invention, not all of them. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0039] Term Explanation: In the present invention, the particle size D10 refers to the particle size corresponding to the cumulative particle size distribution percentage reaching 10% in the microcapsule sample; D50 refers to the particle size corresponding to the cumulative particle size distribution percentage reaching 50% in the microcapsule sample; D90 refers to the particle size corresponding to the cumulative particle size distribution percentage reaching 90% in the microcapsule sample.

[0040] The embodiments of the present invention provide an electrophoretic coating solution, which includes the following components in parts by weight:

[0041] Surfactant 0.1 - 3.0 parts;

[0042] Rheological agent 1.0 - 6.0 parts;

[0043] Water-based resin binder 10 - 35 parts;

[0044] Defoaming agent 0.1 - 2.0 parts;

[0045] Emulsifier 0.1 - 3.0 parts;

[0046] Microcapsules, which include a capsule wall and an electrophoretic solution. The capsule wall is used to coat the electrophoretic solution, and the electrophoretic solution contains electrophoretic particles;

[0047] The weight ratio of the microcapsules to the aqueous resin binder is 3:1 to 8:1;

[0048] The particle size D10 of the microcapsules is 20 - 25 μm, D90 is 45 - 50 μm, and D50 is 27 - 30 μm.

[0049] In a specific embodiment, the electrophoretic solution comprises the following components in parts by weight: 17% - 65% of electrophoretic particles; 30% - 80% of a solvent; and the sum of a charge control agent and a stabilizer is 3% - 5%.

[0050] It should be noted that the electrophoretic particles have the function of reflecting or scattering or absorbing light to achieve the display effect of the final electronic paper. The particle size of the electrophoretic particles is between 10 nm and 2 μm, and mainly includes but is not limited to one of titanium dioxide, carbon black, copper chromite black, iron manganese black, and composite particles. Among them, the composite particles are polymer-modified. The polymer modification is carried out in two steps. The first step is to surface-modify the inorganic particles with a surface modifier, and the second step is to attach an organic monomer to a silane coupling agent through a free radical reaction; the surface modifier includes but is not limited to titanate coupling agents, aluminate coupling agents, silane coupling agents, surfactants, or initiators, and the organic monomers include but are not limited to at least one of methyl methacrylate, aniline, o-methylaniline, lauryl methacrylate, stearyl methacrylate, vinyl silicone oil, and styrene; the initiator is at least one of benzoyl peroxide, lauroyl peroxide, azobisisobutyronitrile, azobisisoheptonitrile, potassium persulfate, ammonium persulfate, and dimethyl azobisisobutyrate.

[0051] The solvent is one of pure water, ethanol, butanol, benzene, toluene, xylene, trimethylbenzene, carbon tetrachloride, dichloromethane, tetrachloroethylene, alkane solvents or isoparaffin solvents, silicone oil, vegetable oil, and castor oil. The charge control agent is at least one of cationic surfactants, anionic surfactants, nonionic surfactants, or zwitterionic surfactants. The stabilizer is polyvinylpyrrolidone.

[0052] In a specific embodiment, the thickness of the capsule wall of the microcapsules is 0.5 - 2 μm. It can be understood that the microcapsules are formed by a coacervation method in which the capsule wall material is deposited on the surface of the electrophoretic solution droplets to form a microcapsule structure. The capsule wall material includes but is not limited to gelatin, gum arabic, carrageenan, carboxymethyl cellulose, etc. The capsule wall of the microcapsules is optically transparent, and the thickness of the capsule wall is 0.5 - 2 μm, which can ensure that the microcapsules have a certain mechanical strength. If the thickness of the capsule wall of the microcapsules is less than 0.5 μm, the mechanical strength of the microcapsules will be reduced, while if the thickness of the capsule wall exceeds 2 μm, it will result in an excessive proportion of the capsule wall material and affect the display performance.

[0053] See further Figure 3 , which is a schematic structural diagram of an electrophoretic display component. The electrophoretic display component includes, from bottom to top, an upper substrate 2, an electronic ink layer 3, an adhesive layer 4, and a lower substrate 5. The electronic ink layer 3 contains microcapsules 1 arranged closely. Generally speaking, the response speed in an electrophoretic display component can be quantitatively described by the Helmholtz-Smoluchowski equation (Equation 1), and its core parameters include the interaction between the migration rate of electrophoretic particles and the electric field strength. Further, to characterize the differences in the motion characteristics of electrophoretic particles with different particle sizes in an electric field, the concept of electrophoretic mobility (Equation 2) is usually introduced, and its physical meaning is the steady-state motion speed of electrophoretic particles under a unit electric field strength.

[0054] It can be seen from the equations that the response speed of the electrophoretic display component is mainly affected by the viscosity of the electrophoretic medium, the particle size of the microcapsules, and the voltage strength of the capsule layer. An increase in the medium viscosity will significantly inhibit the migration rate of electrophoretic particles; a decrease in the microcapsule particle size helps to shorten the migration path of electrophoretic particles, thus shortening the response time; an increase in the voltage of the capsule layer can directly enhance the electric field driving force and increase the mobility.

[0055]

[0056] In the equations, v is the migration rate of electrophoretic particles, η is the viscosity of the electrophoretic solution, ε is the Zeta potential, ζ is the dielectric constant of the electrophoretic solution, is the electric field between two electrodes, l is the distance between two electrode plates, V is the voltage value between two electrode plates, q is the electric charge, and R is the radius of the capsule. Combining Figure 3 it can be seen that the distance between the upper substrate 2 and the lower substrate 5 of the electrophoretic display component is l, and the electronic ink layer 3 is the capsule layer.

[0057] The electrophoretic coating liquid provided by the embodiments of the present invention controls the particle size distribution of microcapsules, and selects microcapsules with a particle size D10 of 20-25 μm, D90 of 45-50 μm, and D50 of 27-30 μm, which helps to improve the electrophoretic response speed and also avoids local deformation (such as flattening or prismaticization) caused by stress concentration of large particle size capsules during the coating drying process; in addition, small particle size capsules shorten the migration path of electrophoretic particles (the migration time is proportional to the square of the path), improve the electric field driving efficiency, and effectively improve the response time. At the same time, the surface area of small particle size capsules increases, and the electric field distribution in the unit volume is more uniform, further accelerating the charge migration. It should be noted that since the microcapsules have a structure of encapsulating the electrophoretic liquid with a capsule wall and the capsule wall is a transparent material, if the particle size of the microcapsules is too small (for example, less than 20 μm), it will cause the proportion of the capsule wall to be too large and affect the display performance. To obtain better display performance, the present invention selects microcapsules with a particle size D10 of 20-25 μm, D90 of 45-50 μm, and D50 of 27-30 μm.

[0058] In a specific embodiment, the electrophoretic coating liquid selects microcapsules with a particle size D10 of 20 μm, D90 of 50 μm, and D50 of 28 μm.

[0059] In other embodiments, the electrophoretic coating liquid selects microcapsules with a particle size D10 of 23 μm, D90 of 45 μm, and D50 of 30 μm

[0060] In some embodiments, the viscosity of the electrophoretic coating liquid is controlled at 20-200 cp. For example, 20 cp, 50 cp, 80 cp, 120 cp, 150 cp, 180 cp, 200 cp. Preferably, the viscosity of the electrophoretic coating liquid is 30-100 cp.

[0061] In some embodiments, the aqueous resin binder includes at least one of aqueous polyurethane, aqueous acrylic acid, aqueous epoxy resin, aqueous styrene-butadiene resin, and aqueous polyester. In a specific embodiment, the dosage of the aqueous resin binder can be 10 parts, 14 parts, 16 parts, 18 parts, 20 parts, 23 parts, 25 parts, 28 parts, 30 parts, 33 parts, 35 parts.

[0062] The aqueous resin binder can be well compatible with the microcapsules, reduce the surface tension so that the microcapsules are well wetted, and help the microcapsules to be evenly dispersed in the coating liquid; further, the present invention selects binders such as aqueous polyurethane, aqueous acrylic acid, aqueous epoxy resin, aqueous styrene-butadiene resin, and aqueous polyester, which helps to improve the mechanical strength of the coating liquid, better protect the microcapsules dispersed therein, and avoid damaging the structure of the microcapsules during the coating process.

[0063] Furthermore, the dosage ratio of the aqueous resin binder to the microcapsules has a great influence on the electrophoretic response time and the pressure resistance performance of the capsules. In specific embodiments, the weight ratio of the microcapsules to the aqueous resin binder is 3:1 to 8:1; for example, 3:1, 4:1, 5:1, 6:1, 7:1, 8:1. By optimizing the dosage ratio of the microcapsules to the aqueous resin binder, the present invention can make the filling of the microcapsule gaps by the aqueous resin binder more sufficient, form a uniform support network around the microcapsules after curing, reduce the rupture of the capsules caused by mechanical extrusion, and effectively reduce the capsule breakage rate.

[0064] In some embodiments, the surfactant includes at least one of acrylic surfactants and polyether surfactants, and may be surfactants such as acrylate esters, polyethers, and acrylic copolymers. In specific embodiments, the dosage of the surfactant can be 0.1 part, 0.5 part, 0.8 part, 1.1 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.5 parts, 2.8 parts, 3.0 parts.

[0065] In some embodiments, the rheology modifier includes at least one of hydroxypropyl methylcellulose and polyurethane. In specific embodiments, the dosage of the rheology modifier can be 1.0 part, 2.0 parts, 3.0 parts, 4.0 parts, 5.0 parts, 6.0 parts.

[0066] The addition of the surfactant and the rheology modifier improves the rheological properties of the coating solution and ensures the uniformity of the film thickness during the coating process.

[0067] In some embodiments, the defoamer includes at least one of silicone defoamers and polymer defoamers. In specific embodiments, the dosage of the defoamer can be 0.1 part, 0.5 part, 0.8 part, 1.1 parts, 1.5 parts, 1.8 parts, 2.0 parts.

[0068] In some embodiments, the emulsifier includes at least one of sorbitan fatty acid esters, polysorbates, polyvinyl alcohol, Spans, and polysorbates. The emulsifier helps to maintain the stability and compatibility of each particle in the system and achieve the stable dispersion of the microcapsules. In specific embodiments, the dosage of the emulsifier can be 0.1 part, 0.5 part, 0.8 part, 1.1 parts, 1.5 parts, 1.8 parts, 2.0 parts, 2.5 parts, 2.8 parts, 3.0 parts.

[0069] The addition of the defoamer and the emulsifier helps to reduce the bubbles and agglomeration phenomena that are prone to occur during the preparation of the coating solution, and further guarantees the coating quality.

[0070] It should be noted that in the technical solution of the present invention, the particle size distribution of the microcapsules is limited, while the production process of the microcapsules is not limited. The production process of the microcapsules can refer to the content disclosed in Patent Application No. 202410094946.2. By controlling the stirring speed in the emulsification stage, the particle size range of the emulsion droplets is 10 - 60 μm. The collected microcapsules are screened through a sieve to obtain microcapsules with a D10 of 20 - 25 μm, a D90 of 45 - 50 μm, and a D50 of 27 - 30 μm, which are used as the microcapsules in the electrophoretic coating liquid of the present invention.

[0071] The embodiment of the present invention also provides a preparation method of an electrophoretic coating liquid, including the following steps: providing each component according to the electrophoretic coating liquid described above, and performing a mixing treatment at 20 - 40 °C to obtain the electrophoretic coating liquid.

[0072] The embodiment of the present invention also provides an electronic ink layer, which is obtained by coating and drying the electrophoretic coating liquid described in the first aspect.

[0073] In some embodiments, the electrophoretic coating liquid is coated on an ITO (Indium Tin Oxide) film, baked at a temperature of 65 - 75 °C for 15 min for curing, and the thickness of the dried paint film is controlled to be 10 - 25 μm, thus obtaining the electronic ink layer. As Figure 1 , which is a photograph of the dried electronic ink layer obtained from a specific embodiment of the present invention. It can be seen that the microcapsules are well-dispersed and closely arranged in the coating, the coating is flat, the water-based resin binder fills the gaps between the microcapsules, and a uniform support network is formed around the microcapsules after curing, and the capsule breakage rate is small.

[0074] It should be noted that after the electrophoretic coating liquid of the present invention is coated and dried, the overall thickness of the dried electronic ink layer will be reduced compared to the thickness during coating. At the same time, the microcapsules will lose water and their volume will shrink significantly, generally about 30% of the original volume. Therefore, in the dried electronic ink layer, the particle size of the microcapsules will be smaller than the thickness of the electronic ink layer. The embodiment of the present invention limits the thickness of the electronic ink layer to be 10 - 25 μm, and more preferably 10 - 15 μm.

[0075] Further referring to Figure 3 , the embodiment of the present invention also provides an electrophoretic display component, which sequentially includes an upper substrate 2, an electronic ink layer 3, an adhesive layer 4, and a lower substrate 5 from top to bottom; wherein, the electronic ink layer 3 is the capsule layer. The electronic ink layer 3 is obtained by coating and drying the electrophoretic coating liquid described in the above embodiments.

[0076] The content of the present invention will be introduced by specific embodiments below. For the convenience of comparison, the surfactant used in the coating solution in the embodiments is an acrylic surfactant; the rheological agent is hydroxypropyl methylcellulose; the aqueous resin binder is aqueous polyurethane; the defoaming agent is a silicone defoaming agent; and the emulsifier is polysorbate.

[0077] Prepare the electrophoretic coating solutions of different embodiments and comparative examples according to the formulations in Table 1.

[0078] Table 1 Formulations of the electrophoretic coating solutions of each embodiment and comparative example (parts by weight)

[0079]

[0080]

[0081]

[0082] Note: The capsule layer thickness refers to the thickness of the electronic ink layer.

[0083] Prepare the coating solutions according to the coating solution formulations of each embodiment and comparative example in Table 1, coat them on the ITO film, bake and cure them at 70°C for 15 minutes to obtain the electronic ink layer, then coat the aqueous polyurethane pressure-sensitive adhesive on the electronic ink layer and cure it at 70°C for 15 minutes, and make electronic paper film sheets in a size of 5 cm * 5 cm, and test the performance and response time of each film sheet. The test results are shown in Table 2.

[0084] Test method: Measure the white L value and black L value of the electronic paper film sheets in the full-white display mode and full-black display mode respectively. In the full-white mode, select five points in the film sheet to take the average, and take points at the four corners and the center respectively. In the full-black mode, also select five points in the film sheet to take the average, and take points at the four corners and the center respectively, and obtain the data in the full-white mode and full-black mode respectively, and provide the calculation basis according to the provided data.

[0085] Response time test: The rise time is the time used for the test sample to switch from the full-black mode to the full-white mode, and the fall time is the time used for the test sample to switch from the full-white mode to the full-black mode. After applying a voltage of 15V to the upper and lower electrodes of the test sample, measure the L value every 2 ms until the L value tends to be stable to measure the rise time, and measure the fall time by measuring the L value every 2 ms in the same way when applying a voltage of -15V.

[0086] Table 2 Test results of each embodiment and comparative example

[0087]

[0088]

[0089] From the test results of Comparative Examples 1 to 6 and Comparative Examples 7 to 12, the response time of the electrophoretic display assembly made of microcapsules with large particle sizes (30 to 80 μm, 45 μm, and 25 to 60 μm, 35 μm) is higher than that of the electrophoretic display assembly made of microcapsules with small particle sizes (20 to 50 μm, 28 μm and 25 to 50 μm, 30 μm) in the embodiment of the present invention. This shows that the coating liquid of the embodiment of the present invention uses microcapsules with particle sizes D10 of 20 to 25 μm, D90 of 45 to 50 μm, and D50 of 27 to 30 μm to improve the electrophoretic response speed.

[0090] Further, in Example 2, Example 4, Example 6 (Example 8, Example 10, Example 10), when the microcapsule particle size and the film thickness are not much different, it can be seen that when the amount of water-based resin binder is large (the ratio is 3:1), it may hinder the penetration of the electric field, resulting in a longer response time; when the amount of water-based resin binder is reduced to 5:1, the response time is significantly reduced, but when the amount of water-based resin binder is further reduced to 8:1, the response time increases again. Too low an amount of water-based resin binder (8:1) may not support the capsule enough, and the electric field is unevenly distributed, resulting in an increase in the response time. The present invention can provide the microcapsules with optimal support and conductivity by adjusting the ratio of microcapsules to water-based resin binders (5:1), thereby further improving the electrophoretic response speed.

[0091] Figure 1 and Figure 2 The electronic ink layer capsules of Example 6 and Comparative Example 6 are shown respectively. It can be seen that the electronic ink layer capsules of Example 6 contain too low an amount of aqueous resin binder (8:1), the microcapsules are arranged loosely, and there are many gaps around them. The particle size of the microcapsules used in Comparative Example 6 is significantly larger than that of the microcapsules of Example 6. At a ratio of 8:1 for the amount of aqueous resin binder, the microcapsules are arranged compactly. It can be seen that the particle size of the microcapsules will affect the ratio of the microcapsules to the aqueous resin binder. For small-particle-size microcapsules (particle size D10 is 20μm, D90 is 50μm, and D50 is 28μm), the optimal amount of aqueous resin binder is 5:1.

[0092] Figure 4 This is a photo of the electronic ink layer of Comparative Example 2. It can be clearly seen that when the amount of water-based resin adhesive is small (3:1), the microcapsules with large particle sizes will be more damaged.

[0093] Furthermore, by comparing the results of Example 3, Example 4, Example 9, and Example 10 with the optimal amount of the aqueous resin binder, Example 3 and Example 9 have quite excellent response times. The microcapsule particle size distributions they adopted are D10 of 20 - 25 μm, D90 of 45 - 50 μm, and D50 of 27 - 30 μm, and the film thickness after drying of the electronic ink layer is 15 μm. This is because after drying, the microcapsules will lose water and their volume shrinks to about 30% of the original volume. Compared with Example 4 and Example 10 with a film thickness of 25 μm, Example 3 and Example 9 have smaller microcapsule particle sizes, which can greatly shorten the moving path of the electrophoretic particles. Therefore, they have the fastest response rate.

[0094] Looking at the comparison further, the microcapsule particle size D10 adopted in Example 3 is 20 μm, D90 is 50 μm, and D50 is 28 μm. The microcapsule particle size D10 adopted in Example 9 is 25 μm, D90 is 50 μm, and D50 is 30 μm. The difference in their response times is not significant, indicating that within the particle size distribution range of D10 of 20 - 25 μm, D90 of 45 - 50 μm, and D50 of 27 - 30 μm for the microcapsules, the best effect of improving the response time can be achieved.

[0095] In summary, for the electrophoretic display component prepared with the coating liquid of the embodiments of the present invention, by using microcapsules with particle sizes D10 of 20 - 25 μm, D90 of 45 - 50 μm, and D50 of 27 - 30 μm, adjusting the ratio of the microcapsules to the aqueous resin binder helps to improve the electrophoretic response speed. Further restricting the thickness of the capsule layer after drying can significantly improve the response time, and the difference in the photoelectric values between the electrophoretic display component and the electrophoretic display component prepared with the coating liquid of large - particle - size capsules is not obvious.

[0096] In the above - mentioned embodiments, the descriptions of each embodiment have their own emphases. For the parts not described in detail in a certain embodiment, reference can be made to the relevant descriptions of other embodiments.

[0097] The above is the specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention can easily think of various equivalent modifications or substitutions, and these modifications or substitutions should all be covered within the protection scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.

Claims

1. An electrophoretic coating liquid, characterized in that: It comprises the following components in parts by weight: Surfactant 0.1-3.0 parts; Rheological agent 1.0-6.0 parts; 10-35 parts of water-based resin adhesive; Defoaming agent 0.1-2.0 parts; Emulsifier 0.1-3.0 parts; A microcapsule, wherein the microcapsule comprises a capsule wall and an electrophoretic solution, wherein the capsule wall is used to coat the electrophoretic solution, and the electrophoretic solution contains electrophoretic particles; The particle size D10 of the microcapsule is 20-25 μm, D90 is 45-50 μm, and D50 is 27-30 μm; the weight ratio of the microcapsule to the aqueous resin adhesive is 3:1-8:

1.

2. The electrophoretic coating liquid according to claim 1, characterized in that The viscosity of the electrophoretic coating liquid is 20-200 cp.

3. The electrophoretic coating liquid according to claim 1, characterized in that: The weight ratio of the microcapsules to the aqueous resin binder is 3:1 to 5:

1.

4. The electrophoretic coating liquid according to claim 1, characterized in that: The water-based resin adhesive includes at least one of water-based polyurethane, water-based acrylic acid, water-based epoxy resin, water-based styrene-butadiene resin, and water-based polyester.

5. The electrophoretic coating liquid according to claim 1, characterized in that: The surfactant includes at least one of an acrylic surfactant and a polyether surfactant; the rheological agent includes at least one of hydroxypropyl methylcellulose and polyurethane; the defoamer includes at least one of a silicone defoamer and a polymer defoamer; the emulsifier includes at least one of fatty acid sorbitan, polysorbate, polyvinyl alcohol, Span, and polysorbate.

6. The electrophoretic coating liquid according to claim 1, characterized in that: The capsule wall thickness of the microcapsule is 0.5-2 μm; the electrophoresis solution comprises the following components in parts by weight: The electrophoretic particles are 17% to 65%; the solvent is 30% to 80%; and the sum of the charge control agent and the stabilizer is 3% to 5%.

7. An electronic ink layer, characterized in that: The electrophoretic coating liquid is obtained by coating and drying the electrophoretic coating liquid according to any one of claims 1 to 6.

8. The electronic ink layer according to claim 7, characterized in that: The thickness of the electronic ink layer is 10-25 μm.

9. The electronic ink layer according to claim 8, characterized in that: The thickness of the electronic ink layer is 10-15 μm.

10. An electrophoretic display assembly, characterized in that: The electrophoretic display component includes an upper substrate, an electronic ink layer, an adhesive layer and a lower substrate from bottom to top; wherein the electronic ink layer is the electronic ink layer described in any one of claims 7 to 9, or is obtained by coating and drying the electrophoretic coating liquid described in any one of claims 1 to 6.

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